This program is concerned with the pathophysiology and treatment of coronary artery disease. There are several major project areas each of which is described briefly, as follows. The physiological and clinical results of saphenous vein graft surgery as treatment for this disease constitute a major part of the program, including a prospective randomized study of the efficacy of this surgery in angina pectoris. The acute effects of surgery on the coronary arteries are being evaluated by studies performed during operation. A number of interventions are being evaluated which have effects on myocardial contractility in coronary disease, especially with regard to drug effects, such as nitroglycerin. The influence of cutaneous and inhaled cold on the dynamics of the coronary circulation is being evaluated as are coagulation factors across the coronary bed in various coronary syndromes. The effects of prolonged cardiopulmonary bypass comprise one project area. A group of angiographic studies are concerned with the natural history and prognosis of coronary disease. Finally, a new project area is concerned with the development of a collagen-fabric vessel prosthesis for aorta coronary bypass grafting.